Come on guys, the ferry ride is one of the best bargains in town, only $2 to cross between HK to Kowloon! But in any case, since every (HK) dollar counts these days, its probably best to stay on HK-side. Sheung Wan to Quarry Bay is about 20min ride on the MTR. SKW may be cheaper and closer, but you will be about 30min (again, MTR) from Central if that is a concern at all to you. Chai Wan is the end of the line, and gets very local so it may prove quite a culture shock in that regard. Bear in mind MTR is the most expensive form of public transport, even if it is (usually) fast and efficient, there's also buses, minibuses, and (cheapest trams which can be reasonable alternatives at times. You'd probably not want to take the tram to work from Sheung Wan to QB every day though, you'd grow old by the time you get to work!